Electric prospecting apparatus.



N0. 68|,654. l Patented Aug. 27, |90I. A. F. ICCLATCHEY.

ELEQTBIC PRUSPECTIIG APPARATUS.

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No. 68I,654. Patented Aug. 27, I90I. A. F. ICCLATCHEY.

ELECTRIC PBOSPECTIIG APPARATUS.

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UNITED STATES PATENT OFFICE.

AUGUSTUS F. MCCLATCHEY, OF AURORA, ILLINOIS, ASSIGNOR TO FREDERICK M.STEELE AND ERNEST DALE OVEN, OF CHICAGO,

ILLINOIS.

ELECTRIC PROSPECTING APPARATUS.

SPECFCATION forming part of Letters Patent No. 681,654, dated August 27,1901.

Application filed April 20, 1900. Serial No. 13,585. (No model.)

T0 ctZZ whom. t may concern,.-

Be it known that I, AUGUSTUS F. MO- CLATCHEY, of Aurora,in the county ofKane and State of Illinois, have invented certain new and usefulImprovements in Electric Prospecting Apparatus; and I do hereby declarethat the following is a full, clear, and exact description thereof,reference being had to the accompanying drawings, and to the letters ofreference marked thereon, which form a part of this specification.

This invention relates to apparatus for locating metals, minerals, ores,and the like.

The object of the invention is to provide means which are simple,eicient, and accurate for determining the presence and location ofminerals, metals, ores, and the like.

The invention consists, substantially, in the construction, combination,location, and arrangement, all as will be more fully hereinafter setforth, as shown in the accompanying drawings, and finally pointed out inthe appended claims.

Referring to the accompanying drawings, and to the various views andreference-signs appearing thereon, Figure l is a view in diagramillustrating the arrangement of circuits and working parts of theapparatus. Fig. 2 is a View in elevation of' a contact piece, pole, Fig.3 is a View in longitudinal section of the same on the line 3 3 of Fig.2. Fig. 4 is a view in transverse section on the line 4 4 of Fig. 2.Fig. 5 is a broken view similar to Fig. 8, showing a displaced positionof the parts. Fig. 6 is a transverse section on the line 0 6, Fig. 2.

In Patent No. 65,910, issued March 20, 1900, to Fred H. Brown, is setforth,described, and claimed a method which consists in establishing acircuit through a definite distance of the earth and measuring theresistance of the earth portion of said circuit, then establishing acircuit through the same distance at various other points in the samevicinity and measuring the resistance of the earth portion of saidcircuits, and finally comparing such measurements, and in a pendingapplication of Fred H. Brown,Serial No.2,562, filed January 24., 1900,is set forth, described, and claimed a construction of apparatus forcarrying such process into practical operation.

In the practical operation of an apparatus and method as set forth anddescribed in the patent and application referred to suitable terminalsare placed in or in contact with the earth a definite and known distanceapart, said terminals being introduced in an electric circuit, the earthbetween the terminals forming part of such circuit. The resistance ofthe earth portion of thisv circuit is then measured. The location of theterminals is then shifted to another point in the same vicinity and withthe terminals spaced substantially the same distance apart as before,and the resistance of the earth between the terminals at the newlocation is then measured and the operation repeated as often as desiredor so as to cover the desired territory being prospected, and thesevarious measurements are then compared with each other. If theresistance so measured at one point varies from that at another point inthe same vicinity to a material degree, then the presence in the earthof an ore, metal, or mineral or other conducting substance at the pointwhere the variation occurs is indicated, and if the resistance someasured at this point is markedly less than the average resistancemeasured in the same vicinity then it is known that ore, mineral, metal,or the like which is present at the point where there is leastresistance possesses the quality of being a better conductor ofelectricity than the earth. By this system of measurements andcomparisons of substantially the same fixed, definite, or known distanceapart ofthe earth terminals, as above indicated, the location of theore, metal, or mineral is determined. The next step in the operation isto determine the depth of the ore, metal, mineral, or other substancebeneath the surface of the earth. This result is accomplished in theapparatus and method referred to by Varying the distance or space apartof the earth terminals. Thus if ore is located fifty feet below thesurface of the earth then its presence will not be indicated if themeasurements of resistance are taken through a distance of one hundredfeet or less of the earthroo that is, if tho earth terminals 'of theapparatus are spaced one hundred feet orless apartfor the reason thatthe current, following the well-known law of seeking a path of leastresistance, will pass directly from one terminal to the other and willnot traverse a longer path from one terminal of the bed or body ofmetal, ore, mineral or the like and thence back to the other terminal.If, however, the distance between the terminals be increased to twohundred feet or more, then the body of the ore, metal, mineral or thelike if of conducting material will offer a path of less resistance tothe current as compared with the resistance offered by the-same distanceof the earth without ore, metal, or minerals. Therefore by th'us varyingthe distance through which the measurements are taken and comparing suchmeasurements the depth of the ore beneath the surface of the earth maybe accurately determined.

It will be readily observed that inasmuch as the location of the bed ofore and of its depth beneath the surface of the earth is determined byasystem of comparing measurements it is not essential that the exactohmic resistance be absolutely ascertained. It is important, however, inthe use of apparatus of the nature above indicated to provide andmaintain an efficient electric contact between the terminals and theearth. It has been "found in practice that when simple metallic 4or gasupon the surface of the metallic terminals and which, forming a coatingfor the surface of the terminal, impairs'the efficient electricalcontact of the terminal with the earth, thus introducing an artificialand y greatly-increased resistance in the earth portion Aof the circuitwhich is to be measured and hence rendering the comparative measurementsunreliable and inaccurate.

The present invention relates to an apparatujs of the character abovereferred to, and is specially designed to avoid the objection oftheintroduction of the element of unreliability mentioned by preventing thedisturbing effects of the presence of a variable resistance at theearth-terminals.

Referring to Fig. 1, A A indicate the earthterminals adapted to beplaced in or in contact with the earth at a suitably-spaced distanceapart. These earth-terminals embody specific features of `constructionwhich constitute the presentinvention and will behereinaftermore fullydescribed: B is a current-generator which may be of any desired type. Inthe parv ticularinstance shown a battery is employed.

C represents a measuring device or indicator which may be of any desiredorsuitable construction-such, for instance, as a galvanometer. Mrepresentsaresistance-measuring apparatus which may be in the form of aWheatstone bridge of the usual or any suitable construction and providedwith the usual connections and circuitbreaking devices. Theconducting-wiresffconnect the earth terminals A A' to the bridge at theproper binding-posts, so that the resistance of the earth portion of thecircuit between the terminals A A and represented by the dotted line Rbecomes the unknown arm or resistance of the bridge. Conductors ff2f3connect the indicating device C and the generator B with the bridge inthe usual or any suitable manner. With the apparatus arranged as abovedescribed a measurement or reading is effected of the indicating deviceand one or both of the earth-terminals are shifted to a new location inthe same vicinity and another measurement or reading is noted and theoperation repeated throughout the space or territory being tested. If abody of metal or mineral or the like is located at a dist-ance below thesurface of the ground less than one-half the distance between the twoterminals, the line of least resistance changes from the line R to theline it" t2. Thus by repeated measurements or readings and a comparisonof the same in dierent places in the same vicinity not only is thepresence of the body of ore, mineral, or the like thereby determined,but also by varying the distance apart of the earth terminals thedistance below the surface of the earth of the ore, mineral, metal, orthe like is also accurately determined.

In carrying out my invention, the special object of which is to preventinaccuracies in the readings or measurements due to the effect of achangeable resistance at the earthterminals,l contemplate interposingbetween the metal of the terminal and the earth or soil a chemicalsubstance having the property of taking up or absorbing or counteractingthe effect of any nascent or free hydrogen or other gases or materialswhich may be developed by the current and which would otherwise adhereto the surface of the terminal IOO IIO

and thereby impair or destroy the efficiency in order to secure adesirable electrical conductivity through the mass, body, or layer ofmanganese dioxid, which is interposed in accordance with my inventionbetween the metal of the terminal and the earth. The suitable and properinterposition of this protecting material between the metal terminal andthe ground or earth may be effected in various ways in practice. InFigs. 2 and 3 I have shown a form of practical device for this purposewhich I have found to be well adapted for use and wherein the handlingand insertion of the same in the earth is facilitated.Referringtothedetailsofconstruction illustrated in said Figs. 2 and 3,II is a metal tube, preferably of copper or brass, having a solidpointed tip L at the end thereof which is designed to be inserted in theground and having at its other end a solid cap or top 7U, which, it'desired and preferably, may be connected by screw-threads with saidtube. I indicates a metal tube which fits closely within the outer tubeH. The tubes I and H are mounted for relative rotation with respect toeach other. This rotation may be secured in any suitable manner-as, forinstance, by providing one of said tubes, as tube I, with a handle I',arranged to extend through a transverse elongated slot h2 in the outertube. Both the outer and inner tubes are provided with openings orapertures (indicated at 7b3 is) which by the relative rotativeadjustment above referred to may be brought opposite or in register witheach other. The slot h2 is made of such length thatv by giving movementto the handle I the inner tube may be revolved through an arc sufficientto either open or close the openings or apertures in the tubes. Kindicates a metal rod which constitutes the terminal proper and which islocated within the inner tube I and is of considerably less size thanthe interior diameter of the tube, so as to leave a space between thesame and the inner surface of the tube. Within this space is placed apacking of the protecting substance or chemicals employed, the latter(indicated at L) being thus interposed between the terminal proper andthe surface of the earth. The rod K is provided with a binding-screw L,by which the conductor leading to the terminal may be attached thereto.In the specific construction shown the inner tube terminates below theouter end of the outer tube and the rod K extends a short distancebeyond the end of the inner tube and within the open end of the outertube. The outer tube is provided with suitable openings, through whichthe wire may be inserted and the binding-screw operated. Theconstruction above described enables the outer tube to be driven intothe ground without interference with the connection of the conductorwith the rod K. The packing referred to and which is interposed in thespace surrounding the rod K consists, as hereinbefore stated, of anadmixture of manganese dioxid and pulverized carbon, the former beingmoistened, if desired, with a solution of sal-ammoniac. This material ispacked into the space between the rod K and the inner tube, while theinner and outer tubes are so relatively adjusted as to close theopenings or apertures therethrough. The terminal so constructed is thenas a whole inserted or driven into the ground. After being inserted intothe ground the inner and outer tubes are again relatively rotated, so asto bring the openings or apertures therethrough into registered relationwith each other and exposing the protecting-packing to contact with theground or soil. Before removing the terminal from the ground theopenings or apertures are again closed, thus avoiding the escape or lossof the protecting agent. The rod K is preferably made of zinc, thoughany other metal possessing suitable conductivity may be employed. Toprevent oxidation of the surface of the rod K, the same may beamalgamated. In practice I prefer to employ a rod made of zinc, becausethe same can be more readily amalgamated. By the construction abovedescribed I prevent the production of a variable resistance at theearth-terminal by the presence of the protecting agent, and the carbonconstituent of such agent affords an efficient electrical contact withthe earth, and thus I eliminate any disturbing feature which would serveto introduce inaccuracies or unreliability in the measurements orreadings of the apparatus. An earth-terminal such as above described.may be employed in connection with either a direct or an alternatingcurrent. A direct current such as is produced by the battery illustratedhas, however, the advantage of being capable of more accuratemeasurement by means of a variable-resistance device, such as alVheatstone bridge, and therefore a direct current is preferred,although I do not limit myself to the use thereof nor to a battery as agenerator.

Having now set forth the object and nature of my invention and aconstruction embodying the principles thereof and having described suchconstruction, its purpose, function, and mode of operation, I desire itto be understood that many variations and changes in the details thereofwould readily occur to persons skilled in the art and still fall withinthe spirit and scope of my invention. I do not desire, therefore, to belimited or restricted to the exact details shown and described; but

What I claim as new and useful and of my own invention, and desire tosecure by Letters Patent, is-

l. In an apparatus for detecting and locating minerals, metals, ores orthe like in the earth, an electric generator, an indicating device and ameasuring device, in combination with terminals arranged to be insertedin the earth, and means for protecting said terminals from the eifectsof electrolytic action, as and for the purpose set forth.

2. In an apparatus for detecting and locating minerals, metals, ores orthe like, earthterminals arranged to be inserted in the earth, and aprotecting agent interposed between the terminal and the earth forprotecting said terminals from the eiIect-s of electrolytic action, incombination with means for measuring the resistance of the earth portionof the circuit between said terminals, as and for the purpose set forth.

3. In an apparatus for detecting-and locat- IOO IIO

ing minerals, metals, ores or the like in the earth, earth-terminalsarranged to be inserted in the earth, a protecting agent arranged tosurround said terminals to protect the same from the effects of variableresistance due to electrolytic action,in combination with means formeasuring the resistance of the earth portion of the circuit betweensaid electrodes.

4. An earth-terminal for use in measuring the electrical resistance ofthe earth, comprising a metallic rod, an apertured casing surroundingsaid rod, and a protecting material interposed between the said rod andcasing, as and for the purpose set forth.

5. A terminal for use in measuring the electrical resistance of theearth, comprising a metallic rod, a tubular casing surrounding the same,said casing provided with apertures therethrough, and a filling orpacking interposed between said rod and casing and consisting of aprotecting agent and a granular conducting material, as and for thepurpose set forth.

6. A terminal for the purpose stated, comprising a metallic rod, asurrounding casing provided with apertures, a packing of protectingmaterial between the rod and the i surrounding casing, and means foropening and closing the openings in said casing.

7. A terminal for the purpose described,

comprising a metal rod,'a surrounding casing consisting of inner andouter apertured shells adapted for movement with respect to each other,and a protecting agent interposed between the said rodand the saidcasing.

8. A terminal for the purpose described, comprising a metallic rod, acasing consisting of apertured inner and outer shells, the outer shellbeing provided-with a solid point and with a head.

9. A circuit-terminal designed to be inserted in the earth andcomprising a metallic rod, in combination with a -protecting materialinterposed between said rod and the earth, as and for the purpose setforth.

10. A circuit-terminal adapted to be inserted in the earth andcomprising a metallic rod, in combination with a combined protectingagent and conducting material surround'- ing said rod and interposedbetween the same and the earth, as and for the purpose set forth.

In testimony that I claim the foregoing as my invention I ax mysignature, in presence of two witnesses, this 17th day of April, A. D.

AUGUSTUS F. McCLATCI-IEY. Witnesses:

C. CLARENCE POOLE,

ERNEST DALE OWEN.

